Climate change is leading to an increasing number of heat days in Austria. These represent a relevant, potentially life-threatening risk for vulnerable groups. KlimaFIT addresses the tension between adaptation strategies that lead to the avoidance of physical exercise when exposed to heat and the targeted strengthening of heat tolerance. The project is investigating what contribution the promotion of active mobility in an integrative, digitally supported heat and mobility management system can make to resolving this tension. KlimaFIT builds on the ‘double ROI of active mobility by combining climate-friendly and health-promoting effects.